Diols monotosylates, rearrangement

Figure 2 shows time conversion curves of 7 in CIXI3 at 100 C. In the absence of TsOH, the disappearance of the diol monotosylate star aft heating for 200 min or longer and occurred in a non-linear manner. The addition of TsC resulted in the marked reduction of heating time for the abrupt consumption of 7, indicating that the acidolysis reaction of 7 t es place autocatalytically. The determination of product distribution showed that 2-phenylcyclohexanone-l and benzoylcyclopentane are obtained in 36 % and 44 % yields, respectively, while TsOH is formed almost quantitatively (Scheme 4). Considering the chemical structures of the ketonic products, it is very likely that 7 imdergoes pinacol-type rearrangement...

The base catalyzed rearrangement of a monotosylated 1,2-diol on alumina, followed by immediate condensation of the sensitive ketone with methylenetriphenylphosphorane, gave the exo-methylene compound below (G. Btlchi, 1966B). 

Base catalyzed pinacol rearrangement of vicinal m-glycol monotosylates is a simple and useful general method for preparing perhydroazulenes. Thus, treatment of cholestane-5a,6a-diol 6-tosylate (115a) with either one mole-equivalent of potassium t-butoxide in f-butanol at 25° or with calcium carbonate in dimethylformamide at 100° gives a quantitative yield of 10(5 6/5H)... 

Thus, treatment of (la,5a,7a)-bicyclo[3.2.0]heptane-l,7-diol with tosyl chloride in pyridine and rearrangement of the resulting monotosylate with one equivalent of potassium /erf-butoxide in tetrahydrofuran for ten minutes gave the tran.s-bicyclo[4.1.0]heptan-2-one trans-5) in 83% yield. When the reaction was allowed to proceed for 19 hours with two equivalents of potassium terf-butoxide, cw-bicyclo[4.1.0]heptan-2-one (cis-S) was isolated in 73% yield most likely this arises from initial formation and subsequent isomerization to the cis-ketone. When the rearrangement was run in deuterated teri-butyl alcohol the product contained less than 33 mol% of deuterium (17% -d, 14% 2-d and 2% 3-d) indicating that the rearrangement proceeds primarily without any kind of enolization. ... 

Monotosylates of c/s-l,2-diols, such as that derived from o -pmene, undergo pinacol-type rearrangements upon treatment with r-BuOK (eq 40). The trans isomer is converted to the epoxide under the same conditions (eq 41). 4-Benzoyloxycyclo-hexanone undergoes a mechanistically interesting rearrangement to benzoylcyclopropanepropionic acid when treated with r-BuOK/ t-BuOH (eq 42). ... 

---